Add comment in Excel

NPOI
Spire.XLS
Download Sample Code

using NPOI.SS.UserModel;
using NPOI.XSSF.UserModel;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace NPOI
{
    class Program
    {
        static void Main(string[] args)
        {
            //Create workbook
            IWorkbook workbook = new XSSFWorkbook();
            ISheet sheet = workbook.CreateSheet("MySheet");

            //Create the drawing patriarch
            IDrawing drawing = sheet.CreateDrawingPatriarch();

            //Create cell and set its value
            ICell cell = sheet.CreateRow(2).CreateCell(2);
            cell.SetCellValue("Comment");

            //Create comment
            IClientAnchor anchor = workbook.GetCreationHelper().CreateClientAnchor();
            IComment comment = drawing.CreateCellComment(anchor);
            comment.String = new XSSFRichTextString("Spire.XLS");
            comment.Author = ("E-iceblue");
            cell.CellComment = (comment);

            //Save the file
            FileStream file = File.Create("ExcelComment.xlsx");
            workbook.Write(file);
            file.Close();

            //Launch the file
            System.Diagnostics.Process.Start("ExcelComment.xlsx");
           
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Spire.Xls;

namespace Spire.XLS
{
    class Program
    {
        static void Main(string[] args)
        {
            //Create workbook
            Workbook workbook = new Workbook();
            Worksheet sheet = workbook.CreateEmptySheet("MySheet");

            //Set the text of the cell
            CellRange cell = sheet.Rows[2].Cells[2];
            cell.Text = "Comment";

            //Add comment
            ExcelComment comment=cell.AddComment();
            comment.Text = "Spire.XLS";
            comment.Height = 100;
            comment.Width = 200;
            
            //Save and Launch
            workbook.SaveToFile("ExcelComment.xlsx", ExcelVersion.Version2013);
            System.Diagnostics.Process.Start("ExcelComment.xlsx");
        }
    }
}

AddComment.zip